1. Field of the Invention
The present invention relates to a moving-picture compression-encoding apparatus, and more particularly, relates to a moving-picture compression-encoding apparatus that selectively compression-encodes a moving picture that has not been compression-encoded and a moving picture obtained by decoding a compression-encoded moving picture.
2. Description of the Related Art
To transmit or broadcast a moving picture, there is known a moving-picture compression-encoding apparatus in which an encoding-processed moving picture is decoded, the moving picture obtained thereby is encoded again by another method, and the resultant moving picture is sent out.
Patent Document 1 describes an encoding apparatus in which encoded data encoded by an encoding method using a motion compensation such as MPEG-2 and H.264 is decoded and picture data obtained thereby is encoded again.
This encoding apparatus solves a problem inherent in the conventional technology in which an enormous amount of operations are needed to generate a motion vector at the time of encoding. In this apparatus, motion vector information is taken out from an encoded moving picture applied as a moving picture to be encoded; the motion vector information is compared with a motion vector value on a periphery of a location that is currently encoded; whether the motion vector can be reused is determined according to a magnitude, etc., of a dispersed value; regarding the motion vector determined as reusable, the motion vector is reused; and regarding the motion vector determined as unreusable, the motion vector is generated inside the encoding apparatus.
Thus, at the time of encoding again the moving picture obtained by decoding the encoded moving picture by another encoding method, when the previous motion vector is reused, the amount of operations required for generating the motion vector in the encoding apparatus can be reduced.
[Patent Document 1] Japanese Published Unexamined Patent Application No. 2007-194818
In the encoding apparatus in Patent Document 1, the moving picture obtained by decoding the encoded moving picture is assumed to be input, and under this assumption, it is only intended to reduce the amount of operations for generating the motion vector at the time of encoding by another encoding method.
Even when a moving picture that has not been compressed is input to the encoding apparatus, an encoding process is the same as a case that an encoded moving picture is decoded and input. That is, apart from processes for generating and calculating the motion vector, the same encoding process is performed, irrespective of whether the input moving picture is a moving picture that has not been compression-encoded or a moving picture obtained by decoding the compression-encoded moving picture. Between the moving picture that has not been compression-encoded and the moving picture obtained by decoding the compression-encoded moving picture, a property of the moving picture, such as encoding noise is imparted, is changed.
In the encoding apparatus in Patent Document 1, the encoding process is performed without taking into consideration of the change of the properties of the moving picture, and thus, in each of a case that the moving picture that has not been compression-encoded is input and a case that the moving picture in which the compression-encoded moving picture is decoded is input, an optimal encoding process in which a quality of the encoded picture is taken into consideration is not performed, which is a problem.